FM Radio Receiver: DIY Compact Audio Player

Executive summary

A basic, highly compact DIY FM radio receiver built using minimal off-the-shelf IC components on a perfboard. Prioritizing simplicity, affordability, and craft, the internal electronics are housed in a custom-designed, aesthetically pleasing 3D-printed enclosure, making it a perfect functional desk object.

Business strategy & value proposition

The problem

  • Complex RF circuits: Building radios from scratch using analog components requires heavy tuning and oscilloscopes.
  • Boring aesthetics: Commercial cheap radios look generic or use poor-quality plastics.
  • Lack of repairability: Modern Bluetooth/FM speakers are glued shut and end up as e-waste when the battery dies.

The solution

  • Integrated IC modules: Utilizes dedicated FM receiver chips (like the TEA5767 or CD9088) to abstract away the complex RF tuning.
  • Custom fabrication: A satisfying, fully 3D-printed enclosure that acts as an acoustic chamber for the speaker and looks premium.
  • Modular power: Uses standard, easily replaceable 18650 lithium-ion cells with standard charging boards.

Product features & UX

Mechanical Tuning Interface

  • Detail: Large, satisfying tactile knobs for volume and frequency tuning.
  • Interaction: Provides a retro, analog feel despite utilizing a modern digital/analog hybrid IC.

Compact Acoustic Case

  • Detail: Thick-walled 3D printed enclosure.
  • Interaction: Designed not just to hold parts, but to maximize the bass response of the small internal speaker.

Technical architecture

High-level stack

Component Technology Role
FM Receiver TEA5767 / CD9088 IC Tuning and demodulating the FM signal.
Amplifier LM386 (or similar) Driving the internal mini speaker.
Power 18650 Battery + TP4056 Rechargeable power supply and management.
Enclosure 3D Printed PLA/PETG Housing components and improving acoustics.

Core systems logic

  1. Tuning: The user turns a potentiometer (or rotary encoder) which alters the voltage/I2C signal sent to the FM chip.
  2. Demodulation: The FM chip locks onto the frequency and outputs a weak, line-level audio signal.
  3. Amplification: The audio signal passes through an analog amplifier IC, driving the physical speaker membrane.

Handling edge cases

  • RF interference and noise: Switching regulators or nearby microcontrollers inject buzzing into the audio.
    • Mitigation: Use linear low-dropout regulators (LDOs) for power instead of buck converters, and keep the antenna trace far from digital lines.
  • Poor antenna reception within a plastic case:
    • Mitigation: Coil an internal wire specifically cut to an FM quarter-wavelength (~75cm), or add a rigid external SMA telescopic antenna.

Future roadmap

Phase 1 (MVP)

  • [ ] Select and order the FM receiver module (TEA5767/CD9088) and amp.
  • [ ] Design the basic circuit schematic (receiver, amp, speaker, battery).
  • [ ] Test the circuit loosely on a breadboard to verify reception.

Phase 2

  • [ ] Solder the final layout onto a compact perfboard.
  • [ ] Design the CAD model for the custom 3D printed case and speaker grill.
  • [ ] Print the enclosure and test the acoustic fit.

Phase 3

  • [ ] Refine the antenna design and add proper internal shielding (copper tape) if noise is present.
  • [ ] Add a small OLED display via an Arduino Nano to show the exact station frequency (if using TEA5767).